Operations, such as surveying, drilling, wireline testing, completions, production, planning and field analysis, are typically performed to locate and gather valuable downhole fluids. Surveys are often performed using acquisition methodologies, such as seismic scanners or surveyors to generate maps of underground formations. These formations are often analyzed to determine the presence of subterranean assets, such as valuable fluids or minerals, or to determine if the formations have characteristics suitable for storing fluids. Although the subterranean assets are not limited to hydrocarbon such as oil, throughout this document, the terms “oilfield” and “oilfield operation” may be used interchangeably with the terms “field” and “field operation” to refer to a field having any types of valuable fluids or minerals and field operations relating to any of such subterranean assets.
During drilling and production operations, data is typically collected for analysis and/or monitoring of the operations. Such data may include, for instance, information regarding subterranean formations, equipment, and historical and/or other data.
Data concerning the subterranean formation is collected using a variety of sources. Such formation data may be static or dynamic. Static data relates to, for instance, formation structure and geological stratigraphy that define geological structures of the subterranean formation. Dynamic data relates to, for instance, fluids flowing through the geologic structures of the subterranean formation over time. Such static and/or dynamic data may be collected to learn more about the formations and the valuable assets contained therein.
In particular, seismic survey typically is employed for purposes of discovering hydrocarbon (oil and gas) deposits in geological formations. In the seismic survey, sources generate seismic waves, or signals, which propagate into the geological formations and create pressure changes and vibrations along their way. Changes in elastic properties of the geological formations scatter the seismic waves, changing the waves' directions of propagation and other properties. Part of the energy that is emitted by the sources reaches seismic sensors. Some seismic sensors are sensitive to pressure changes (hydrophones), others to particle motion (e.g., geophones), and industrial surveys may deploy only one type of sensors or both. In response to the detected seismic events, the seismic sensors generate electrical signals to produce seismic data. Analysis of the seismic data can then indicate the presence or absence of probable locations of hydrocarbon deposits.
Traditional seismic data processing is based on the premise that the seismic measurements are insufficient for purposes of resolving the thickness of a bedding layer, which is less than one quarter of the wavelength of the seismic signal. However, a hydrocarbon deposit may be contained in a relatively thin bedding layer that has a thickness that is less than the one quarter wavelength threshold. Examples of such thin bedding layers include sediment layers that are formed by streams, rivers, bay deposits, turbidic flows and the fragmented remains of talus slopes that are generated by wave action against reefs. Therefore, the one quarter wavelength limitation precludes the discrimination of relatively thin geological features and, in general, may prevent the discovery of certain oil and gas deposits.